What has been people’s experiences with vets and FIP?

When out cat sally got sick , are vet was almost useless, the best he would say is well she may have FIP (even though he didn’t do anything other than blood work which she tested for FeCV at the 1:400 level and the 1:1600 level) and he said they don’t really treat cats with FeCV / FIP and referred us to a clinic that does but that was the extent.

Then with another cat we have that got blood work done (she also tested at both levels for FeCV but is otherwise not showing any other signs so we are not worried) well this vet (different vet, same clinic ) was only slightly better. However she was still not able to give any super useful information.

Anyways it’s super frustrating working with the vets.

How have other peoples experiences been ?

And when we take sally back at 30 days. Is there anything, other then blood work we should ask to have done?

Thanks

Edit: At 30 days if we want to get a more concrete yes/no answer to if she has FIP , what do we do ask?